just a prototype

dns-server-prefork.pl

#!/usr/bin/env perl
use strict;
use warnings;
use utf8;
require Net::DNS::Nameserver::Prefork;

my $app = sub {
    my ($qname, $qclass, $qtype, $peerhost, $query, $conn) = @_;
    my ($rcode, @ans, @auth, @add);
    ...;
    return ($rcode, \@ans, \@auth, \@add, { aa => 1 });
};

my $server = Net::DNS::Nameserver::Prefork->new(
    host => '0.0.0.0',
    port => 5053,
    tcp_max_workers => 2,
    udp_max_workers => 4,
) or die;

$server->run($app);